1. Field of the Invention
The present invention relates to ink jet recording heads for use in ink jet recording systems or the like.
2. Description of the Related Art
An ink jet recording head (hereinafter referred to as a “recording head”) typically has a substrate that includes at least: a plurality of discharge ports through which ink is discharged; a channel communicating with each discharge port; a supply opening for supplying the ink to the channel; and an energy producing element that applies discharging energy to the ink in the channel. The recording head also has: a support member supporting the substrate; and an ink supply passage defining member for supplying ink to the substrate. A Si (silicon) substrate is generally used as a substrate. The ink supply passage defining member is formed from plastic or a similar material. A channel forming member is formed from a photosensitive resin, especially, from a catalyst for photo-polymerization and a cationic polymerization resin, which can be polymerized by light. Examples of such a catalyst for photo-polymerization include photo-acid generating agents containing fluorine atoms, such as iodonium salt of antimony fluoride, sulfonium salt of antimony fluoride, and sulfonium salt of phosphorus fluoride in terms of photo-reactivity.
U.S. Pat. No. 6,592,202 discloses a recording head in which a rubber member as a part of an ink passage is used between a supply passage and a support member supporting a substrate. Such a rubber member is formed from rubber cross-linked by a metal oxide such as ZnO or MgO. Examples of the cross-linked rubber include butyl rubber and halogenated butyl rubber.
In the recording head disclosed in the foregoing publication, a channel forming member contains fluorine atoms composing a photo-acid generating agent or the like and, in addition, the rubber member may contain metal. In such a case, a very small amount of metal that is a cross-linking constituent contained in the rubber member may dissolve in the ink. The metal may be combined with the fluorine of the channel forming member, with the result that a compound of metal and fluorine may be deposited. Such a deposit may block a discharge port or stay near the discharge port, leading to discharge failure.